1/14/15 CELL I. BASIC CELL COMPOSITIONA. Plasma membrane = Cell membrane – surrounds cell and gives it form 1. Structure: 2 layers of phospholipids with proteins scattered throughout a. Proteins : in membrane or “float” on surface b. Glycoproteins: proteins with carbohydrate (sugars) attached 2. It is selectively permeable. Determined primarily by size, charge, and solubility of molecule. Regulates movement of material in/out of cell 3. Functionsa. Passive Transport (no energy)i. Diffusion: Some SMALL materials may diffuse/pass through the cell membrane where molecules move from a higher concentration to a lower concentration b. Active Transport (energy required) LARGE particles must be transported actively:TWO TYPES:i. Exocytosis: process by which cellular materials EXIT the cell - materials packaged within vesicles (small sacs) - vesicles fuse w/cell membrane and release contents outside of cellii. Endocytosis: process by which materials arebrought INTO the cell. (3 types) - Phagocytosis: “cell eating”; ingestion of large particles - Pinocytosis: “cell drinking” ingestion of fluid and small particles- Receptor-mediated endocytosis: substances bind to receptors where the membrane is indented= coated pit, and a clathrin (special protein)-coated vesicle is formed- Endocytosis-exocytosis animation 4. Specializations of plasma membrane:a. microvilli: nonmotile, help increase surface areab. cilia: motile, move substances over the surface of stationary cells.c. flagellum: motile, whip-like structure that moves cells B. Cytoplasmic Organelles1. Mitochondriona. Makes ATP (adenosine triphosphate, energy molecule) 2. Ribosomes - involved in protein synthesis(synthesis=production)a. two kinds:1. free ribosomes: makes proteins for the cell2. ribosomes attached to ER: make proteins for export3. Endoplasmic Reticulum (ER) - a network of tubules used to transport & synthesize (produce) materialsa. Rough ER - has ribosomes on walls. Transports and modifies proteins made by the ribosomesb. Smooth ER – no ribosomes attached to it - synthesizes lipids, mainly steroids- detoxify drugs and alcohol (breaks it down so itsnot harmful)4. Golgi Apparatus: several C-shaped sacs near the nucleusa. packages material for secretion b. forms lysosomes5. Lysosomes - contain digestive enzymes a. enzymatically breaks down internalized material and old organelles ”garbage men” of the cell autolysis? 6. Centrioles – needed for cell division C. Nucleus1. Nuclear Envelope (Nuclear Membrane): It has nuclear pores and is selectively permeable2. Nucleolus – contains protein and RNA3. Chromatin - coiled mass of DNA (1/2) wrapped around proteins (1/2)II. DNA (= deoxyribonucleic acid) COMPOSITION/REPLICATIONA. it is made up of nucleotides (each consists of a phosphate group,sugar, and base) B. Shape: double helix C. Prior to cell division, the DNA "unzips"1. free nucleotides will attach to the two half-ladders, forming two identical DNA strands = replication Which of the following is responsible for protein production?a. Mitochondrionb. Lysosomec. Smooth endoplasmic reticulumd. Rough endoplasmic reticulume. Ribosome
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